Democratic Presidents and Republican Presidents choose very different types of wars, for very different types of purposes; and the 2003 invasion of Iraq was characteristically very much the type of thing that Republican Presidents tend to do. History makes this clear.
World Wars I and II were Democratic wars, which Democratic Presidents (Wilson and FDR) waged and won, in the face of stiff Republican (and Dixiecrat, equally conservative) "isolationist" opposition. Both Democratic Presidents wanted the U.S. to enter both of those wars, which were started not on their own initiatives, but on the initiatives of actual foreign aggressors. And these Democratic wars were correct wars for the United States to enter. We didn't start them; we didn't invade; U.S. national security really was being threatened by hostile foreign powers, on both of those occasions. By contrast, the Vietnam War was a misbegotten war that would never have been waged if the Democrat JFK had remained President, and that Lyndon Johnson entered only with great reluctance, doing so only because he feared the demagogic accusations, from Republicans, alleging Democrats to be "soft on communism." This misbegotten Republican-driven war in Vietnam was then adopted by the fanatically anti-communist Republican Party, which had succeeded at goading Americans to invade Vietnam. Republican President Richard Nixon continued this war by carpet-bombing not just Vietnam but much of Southeast Asia, before he finally surrendered in defeat and withdrew from Vietnam -- with Nixon's anti-Vietnam-War Democratic opponent George McGovern and other anti-war Democrats receiving the blame from the power-worshipping American masses for this defeat, as if "winning" in Vietnam would have been realistically possible, or even important.
Vietnam was thus a Republican war that started on a Democratic watch. Of course, it ended on the watch of a Republican President, Nixon, who extended it from 1968 to 1975 by his trying to bomb North Vietnam "into submission," before finally deciding to flee Vietnam, chaotically, on 30 April 1975.
In a profound sense, there is no truthful analogy between the way that the U.S. came to invade Vietnam in 1964, and the way that we invaded Iraq in 2003. George W. Bush knowingly lied about the evidence in order to win the support of the American people to invade Iraq. (I document this in my 2004 IRAQ WAR: The Truth. I show there that what he lied about was not that WMD were being built and stockpiled in Iraq, but that he possessed solid evidence of that; he actually possessed none whatsoever, and his Administration cooked up the fraudulent "evidence" that he did cite -- so he definitely lied the U.S. into that invasion. That's treason, and he did it.)
Lyndon Johnson didn't lie the country into invading Vietnam -- he was authentically deceived, in that instance, by wrong intelligence. (For Bush, massive intelligence-failure was his excuse and rationalization; for LBJ, a single intelligence-failure and tragedy was his reality and the true explanation for why we invaded.) "N.S.A. officials deliberately distorted critical intelligence to cover up their mistakes," as Scott Shane reported in the 31 October 2005 New York Times, under the page-one headline, "Vietnam Study, Casting Doubts, Remains Secret." Shane revealed that the NSA, presumably late in the Bill Clinton Administration, had commissioned a historical investigation of precisely how the U.S. had come to invade Vietnam. "The N.S.A. historian " concluded that they had done it not out of any political motive but to cover up earlier errors." Key here were "a pattern of translation errors" and other blunders, which (in ways that Mr. Shane failed to discuss) caused officials to believe -- it turned out tragically mistakenly -- that the North Vietnamese had attacked U.S. boats, on 4 August 1964, in the Gulf of Tonkin. Then, "midlevel agency officers " deliberately skewed the evidence" to fit those previous errors, and President Johnson consequently ordered a U.S. military response. However, the Bush Administration suppressed this massively important report, when it was completed in 2001, and did not release it to the public, because Bush was then planning to invade Iraq (he called it "regime change in Iraq"), and he knew that his final and last-ditch defense against possible accusations which might come his way, saying that he had deceived the nation into an invasion of Iraq, would be that a Democratic President had done the very same thing in 1964. This false argument would be Bush's trump card against the Democrats, and he knew it and he wanted to preserve that option. The New York Times, being a Republican newspaper in its news reporting (even though Democratic in its editorials) characteristically thus played down, in this news report, its actually key revelation, which should have been its headline and its lead sentence -- that President Johnson actually had been misled by an intelligence-failure, into invading Vietnam. This crucial information was instead buried, because of what had motivated the Bush Administration to withhold the publication of this key historical study in the first place. This news report acknowledged only that, in 2002, "government historians argued that it should be made public. But their effort was rebuffed by higher-level agency policy-makers, who by the next year  were fearful that it might prompt uncomfortable comparisons with the flawed intelligence used to justify the war in Iraq, according to an intelligence official familiar with some internal discussions of the matter." Wow! Higher-level policy-makers having this "fear," at that time, from 2002 on through 2005, which was both prior to and following the invasion of Iraq, displays the Bush Administration's having actually been uncertain about Saddam's alleged "weapons of mass destruction" -- the purported cause de guerre for us to invade. In other words: Bush's team were careful to hide this report, because of their wish to retain the cover that LBJ, too, had invaded under a false pretext -- i.e., that lying the nation into a war wasn't "just" a Republican practice. But it was. And this Times news story buried that startling and crucially important revelation.
This Clinton-initiated study was being suppressed in the lead-up to Bush's first congressional mid-term elections, when the President's ability to get his programs passed through Congress would be largely determined by what the voters would decide. This news revelation, of not only intelligence-manipulation but political manipulation of the American public, by the Bush Administration, and of a truly tragic and innocent intelligence-failure by the Johnson Administration, would have been disastrous for Bush, and was quite possibly the most important news of all, not only within this particular NYT article, but perhaps throughout the entire G.W. Bush Presidency. This information discredited the myth that President Johnson had "lied the nation into war," just as George W. Bush was now actually implicitly exposed here as having been doing: manipulating the public into approving, and then into accepting, this invasion and occupation of Iraq. Removing the Johnson-Vietnam prop from Bush might have effectively delegitimized the Iraq invasion in American eyes, and so Bush was evidently determined to retain the prop, so as to retain cover for his own actual evil -- his treason against the nation he ruled.
This news story thus exhibited important history about not only the old Vietnam War, but also the new Iraq War. However, instead of its being the subject of a major news story in the Times, it was merely buried in one. After all, the Times had, itself, been the chief newspaper that had worked hand-in-glove with the Bush Administration to deceive the American public into believing that solid evidence existed indicating that Saddam Hussein was stockpiling huge quantities of WMD for possible use against the United States. The Times was (as my Iraq War book documented) heavily complicit with President Bush in deceiving the American public into the 2003 invasion of Iraq.
Thus, this blockbuster revelation, on 31 October 2005, should have been the story's focus, but was instead buried by the Times. As a consequence, the American public continued (and still continues) to believe that, if the Republican G.W. Bush had lied the nation into war in 2003, then Democrat Lyndon Johnson had done virtually the same thing in 1964; and, so, it looked as if what was rotten here was American democracy itself, and not a fascist G.W. Bush government. This is the impression that Bush undoubtedly wanted to convey; and, so, the Times buried it, instead of having headlined and led with it -- which might have made an enormous amount of difference, and maybe even turned the 2004 Bush-Kerry contest (in which Vietnam was a major issue). (How long had the Times sat on the story; could they have published it before the 2004 elections; did Bush hold it up, or did the Times?)